הרב ד"ר דוד יעקב הלוי סג"ל סימונסן היה רבה הראשי של דנמרק, ביבליופיל, חוקר יהדות, ומומחה לשפות שמיות.
David Jacob Simonsen was born in Copenhagen, Denmark. He studied Oriental languages at the University of Copenhagen, and received his rabbinical training at the Jewish Theological Seminary in Breslau, one of the centres for "Wissenschaft des Judentums", a movement advocating the scientific study of Jewish history, literature, and culture in addition to the classical sources of Judaism.